Various embodiments of the invention relate generally to an acoustic sensor and particularly to the performance of the acoustic sensor.
Transducers of MEMS acoustic sensors have a frequency response with a gain peak that is quite steep relative to the remainder of the acoustic sensor's frequency response. Sounds or speech heard by a user of the MEMS acoustic sensor at frequencies of the gain peak or thereabout are unpleasant. An example of this unpleasantness is harshness of the voice. In some cases, the gain peak can degrade the intelligibility of speech that is recorded by the acoustic sensor, because it amplifies only the portions of the speech that are at frequencies substantially close to the gain peak. MEMS acoustic sensors employed in mobile devices, such as cell phones, exhibit additional unpleasant sounds because their gain peak shifts due to environmental changes. Another undesirable effect of high gain peak is noise amplification.
Therefore, the need arises for gain peak reduction in a higher performing MEMS acoustic sensor.